Status of "Bulletin 17B" Flood-Frequency Guidelines In Reply Refer To: April 14, 1988 WGS-Mail Stop 415 OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 88.06 Subject: Status of "Bulletin 17B" Flood-Frequency Guidelines The Hydrology Subcommittee of the Interagency Advisory Committee for Water Data has completed a study of whether its flood-frequency guidelines (Bulletin 17B) are meeting the needs of Federal agencies and whether the guidelines should be revised or extended. As part of this study, a question- naire was distributed (Surface Water Branch Technical Memorandum 85.05, dated February 14, 1985) to identify problems and solicit suggestions for improve- ment of the Bulletin 17B methodology. A copy of the study team's report to the subcommittee is attached. The study found that a number of problems are sometimes encountered in using Bulletin 17B and recommended that a series of pamphlets be prepared to provide additional guidance in solving these problems. The Hydrology Subcommittee agreed to form a work group to follow up on this recommendation. The main conclusions of the study, however, are that on the whole the guide- lines prescribe technically sound procedures, that no substantial problems within the scope of the guidelines have been identified that cannot be handled by means included in the guidelines, and that no breakthroughs in statistical practice have occurred to provide feasible, substantial, and clearly superior technical alternatives to the Bulletin 17B methodology. Therefore the Hydrology Subcommittee has decided that replacement or revision of Bulletin 17B is not warranted at this time. U.S. Geological Survey (USGS) offices that perform flood-frequency analyses should continue to follow the Bulletin 17B guidelines until further notice. These guidelines were distributed by Surface Water Branch Technical Memorandum 82.04, dated October 16, 1981. It should be noted that the guidelines include provisions for the properly documented use of alternative methodologies where necessary. Computer program J407, described in the WATSTORE Users Guide, volume 4, chapter I.C, continues to be the USGS implementation of the Bulletin. This program also has been modified to run on the Prime computer, and it is expected to be included in the next release of the ANNIE/WDMS system (see Office of Surface Water Technical Memorandum 87.08 dated, April 21, 1987). Charles W. Boning Acting Chief, Office of Surface Water Attachment Distribution: FO-LS; SL OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 88.06 2